1. Field of the Invention
The present invention relates to a magnet member.
2. Related Background Art
R-T-B-based rare-earth permanent magnets have currently been in use in various fields such as motors because of their high magnetic characteristics. However, the R-T-B-based rare-earth permanent magnets have relatively low corrosion resistance, since they contain as main ingredients a rare-earth element R and a transition metal element T such as iron which are easy to oxidize. When a magnet corrodes, its magnetic characteristics deteriorate and fluctuate. When an R-T-B-based rare-earth permanent magnet is secured to a metal component (yoke) of a motor through an adhesive, a corrosion product such as rust may occur in a contact part between the magnet and the metal component. The corrosion product lowers the adhesion force. For eliminating these problems, a method forming an Ni plating film or Ni alloy plating film as a protective film having excellent corrosion resistance on a surface of the R-T-B-based rare-earth permanent magnet has been employed widely.
When incorporating an R-T-B-based rare-earth permanent magnet equipped with an Ni plating film as a protective layer into a component, high adhesion is required through an adhesive between the Ni plating film and the component. However, the Ni plating film may fail to adhere fully to the component depending on the environment for use. For overcoming this problem, Japanese Patent Application Laid-Open No. 5-198414 proposes a method covering an R-T-B-based rare-earth permanent magnet with an Ni plating film and further forming a chromate coating film on the Ni plating film.